Minolta Rokkor MC PG f 1.2

MrFizzbin · Aug 14, 2012

Greetings and salutations all. This is my first post by the way. I was wondering if you could assist me on a lens I would dearly like to obtain. I have a good possibility in getting the above-mentioned lens. There is a hitch however: The present owner states that the aperture setting is stuck at f 1.2 . He says it used to work fine, but hasn't used it in a few years. He believes reason the aperture is stuck "is that the internal lubrication has migrated onto the aperture blades and oiled them so they would need to be cleaned" . Now, I really have wanted to get this lens and am willing to take the risk to a certain extent. My problem is: 1). getting it professionally repaired seems like it's going to be an issue. Preliminary searches for my area (Montreal, Canada) has come up negative. So, I am floating a request to anyone out there if they know of anyone who would service a Canadian customer. My alternative is to see if I can repair myself. I did some research and could pull off some minor disassembling to clean the aperture blades.. but nothing more. So my second question is: would you recommend repairing myself, or am I nutz to even consider this "big in a polk"?

Anyways, and input would be greatly appreciated.

Sirius Glass · Aug 14, 2012

It is a great lens, however cameras and lenses that have sat for years require a CLA [Clean, Lubricate and Adjust]. Do not even think this is a do you yourself job. This requires a professional repairman. I do not know of someone in your part of Canada to recommend, nor do I have an idea of the cost. You are better off passing on this one. Another and better one will come along.

Welcome to APUG

silentworld · Aug 15, 2012

Try Toronto Camera Service
http://www.torontocameraservice.com/

They fixed my MC 35mm F1.8 with oil on the blades as well.

Andrew K · Aug 15, 2012

Welcome to APUG..

In a previous life (when I was a camera technician) I repaired a couple...it's one of the easiest 58mm/1.2 lenses I've repaired....especially compared to something like a Canon R sereies 58/1.2...

Would I recommend tackling the repair? Only if you have cleaned the diaphragm blades on several lenses in the past, and are comfortable dismantling lenses..

The lens shouldn't present much of a problem to an old camera technician - someone who has been in the repair business for say 20+ years...

I'd happily service it for you - except that I'm in Australia, and the postal service between our 2 countries can at best be described as terrible.....

To be honest whether you would/should buy it depends on how much he wants for the lens.....have a look at what they've sold for on ebay in the past, and if you can get it for half that price then it's worth considering...

They are a great lens (I've owned a couple). From personal experience I think you need to ask yourself one question - are you ever going to stop it down past full aperture??

Cheers

Andrew

MrFizzbin · Aug 15, 2012

Thanks for the quick reply folks. Right now, it's sitting at $250.00 with 5 days to go. This lens has been going for $400-500.00 on average from what I can see. It's getting close to what I figure I want to pay for a lens with stuck aperture blades. There are a few youtube repair videos floating around, and as you say Andrew, it's seems to be an easy disassemble. If I can clean the blades then great..if not, 1.2 it is. Guess I'll wait till we get closer to the final hours of this auction ... In the meantime I'll visit your recommended site Silent..Thanks again all.

E. von Hoegh · Aug 15, 2012

MrFizzbin said:
Thanks for the quick reply folks. Right now, it's sitting at $250.00 with 5 days to go. This lens has been going for $400-500.00 on average from what I can see. It's getting close to what I figure I want to pay for a lens with stuck aperture blades. There are a few youtube repair videos floating around, and as you say Andrew, it's seems to be an easy disassemble. If I can clean the blades then great..if not, 1.2 it is. Guess I'll wait till we get closer to the final hours of this auction ... In the meantime I'll visit your recommended site Silent..Thanks again all.

You don't know it's oil on the blades. You won't know anything about it until you have it disassembled and diagnosed. You are truly buying a pig in a poke.

Jeff Kubach · Aug 15, 2012

You could look up KEH.

Jeff

Sirius Glass · Aug 15, 2012

Les Sarile · Aug 15, 2012

There were two versions of MC. The older one has metal focus ring while the newer version has rubber. I have the newer version and it is a massive chunk of glass!

Good luck!

MrFizzbin · Aug 16, 2012

This one is the older version: milled metal focus ring and silver aperture ring. It's serial number starts in the 200 range. Not sure if this one would have a radioactive coated rear element. My research is not conclusive on this point, but the serial number would put it as a strop possibility. It shows no sign of yellowing. (Even if it did, I wouldn't be to concerned as there are ways to treat it. Once again, the aperture is stuck wide open at f 1.2 . I'd be more worried if it was stuck at f 16. It also has somewhat of a sentimental value as well. My father had bought the Minolta SR 7 back in the 60's . He passed away a few years later when I was very young. By the early 80's, (in my foolish youth), decided to try to see if I could sell the camera ( and yes, ..It had a MC PG 58mm f 1.2). I needed the money to get a zoom lens for my newly acquired Minolta X 700 , lol. Well, the shop wasn't interested in the SR 7 of course, but he was more than happy to buy the lens. (Don't remember how much he bought it for..certainly less than $100.00 ). Funny how things come full circle ...

leicarfcam · Aug 19, 2012

If this is the lens I was looking at earlier today I suspect all that is wrong is oil on the blades that have locked it up. Oil from the helicoid will over time outgas and deposit on the blades making them sluggish and after sitting up for long periods of time will not move..

This is an easy fix for a repairman.

If it goes over $375 I'd forget it since the added cost of a CLA would push it over real value..

MrFizzbin · Aug 19, 2012

Leicarfcam ... My exact sentiments . Above that, and I will wait for the next opportunity. And now we wait ... I'll keep you posted if I win or not.

ic-racer · Aug 19, 2012

It is stuck on 1.2? What is the problem. You are not going to pay all that money and then stop it down are you?

MrFizzbin · Aug 20, 2012

Lol.. No it's definitely a fast lens, that I'll be using mostly at 1.2. But I would like to be able to stop down at 2.0 though. In any case..I won the bid! Now we wait for delivery. Hopefully Canada Customers won't hold it up long or charge me an arm and a leg in customs fees (I doubt it).

MrFizzbin · Aug 29, 2012

It's arrived

And I have had time to reference other sites regarding the disassembly of the lens as well as getting the required tools. Everything was in place and i proceeded with instructions accessed from two sites ( http://www.pbase.com/pganzel/58mm_rokkor_disassembly and http://forums.dpreview.com/forums/readflat.asp?forum=1024&message=22408057&changemode=1 Well... I ran into an issue e mediately.. won't go into details but .. I have access the aperture assembly and am in the process of cleaning them. I expect the re-assembly to be the proverbial %&%^& . Will keep you posted.

MrFizzbin · Aug 30, 2012

Uh Oh ...

Well, the apertures are all cleaned up and functioning well. The dissambly didn't go as planned though, and as a result ended up messing with the helicoid assembly. This I believe is causing me so much headaches. I get to the point where everything seems to be fitting and interacting okay, but as soon as I screw in the final 4 screws into the mount plate that screw into the aperture ring (that screws into the main body ring), everything goes south. The focus ring that used to focus from the minimum to infinity, stops well short of infinity. The aperture adjust ring doesn't open the blades, or at lrast not completely.. I believe it centers aroung the 2 piece helicod assembly. If anyone out there has any experience or suggestions (other than send it in to a camera repair shop*), PLEASE feel free to help! (*repair shop is a definate possibility, but is seems that I am so close to having this working propperly.

Andrew K · Aug 31, 2012

Oh oh! if you've split the helicoid and not marked where things were when it came apart then you're in for a bit of fun...

Your main problem is the front part of the helicoid - the one with the coarse thread (the one the front lens group is screwed into) is in the wrong thread and is not going back far enough into the lens body to allow infinity focus. You need to take the rear mount off, then unscrew the front helicoid, and restart the helicoid one tread to the right, then reassemble.

You may need to do this a few times, as you amy also need to adjust the rear helicoids position (the one with the fine thread) around 1/5th of a turn each time until you get it in the right position.

The right position is one where the aperture unit is in the right position so yu can screw the rear mount back on without the aperture unit being tight, and that allows you to focus the lens to infinity..

I hope this makes sense?? If not send me a PM and I'll try to answer your questions

MrFizzbin · Aug 31, 2012

That is exactly what happened. And you know..I had the best setup... I had a video camera ready to record the entire disassembly process. Pen and note pad at the ready. Every conceivable tool at the ready just in case. But then, I got rolling and .. well, you know the rest. [FONT=Arial, Helvetica, sans-serif]I had been at it for 9 hours straight and decided to throw in the towel. After 2 days of this stuff..I had my fill and was was going to send it to a repair service in Toronto, since there aren't any in Montreal that I am aware of. So I assembled it in the way I thought would make most sense, not really expecting the focus or aperture ring to really work. But God must look after idiots, because would you believe it, the focus ring worked as did the aperture settings. After ready your reply, I checked out the infinity focus, ND Unfortunately, it does not focus to infinity. I made a post in a Flickr group called "Minolta Rokkor f/1.2" where I posted my situation. I got one reply very similar to yours, without mentioning having to possibly adjust the real lens group however. I REALLY would like to avoid a complete disassemble once again.. Can I not, in your opinion, adjust the front helicoid by going in from the front only? (Removing the front lens group via a spanner wrench and adjusting from there? Oh.. and if I do this...just want to make sure my "right" and your "right" are the same..Lol.. When you say "[/FONT]restart the helicoid one tread to the right, then reassemble.", I am I to assume you are A) looking down the barrel from the rear lens group out to the front lens group or, B) facing the front lens group looking down to the rear lens group? This is going to turn out into "Helicoid hell" I am sure.

ic-racer · Aug 31, 2012

Andrew K said:
Oh oh! if you've split the helicoid and not marked where things were when it came apart then you're in for a bit of fun...

+1

MrFizzbin · Sep 1, 2012

Well, I managed to get the focus to go to infinite, and the arpeture works just fine. Took me about 2 hours, but in the end all is well... except.. Now I have an issue with the mount ring. Specifically, the lever that stops down the aperture blades is extremely stiff. The lever will not move unless I physically move it myself. The aperture step down pin from within the aperture assembly is working fine by the way. But between the spring on the mounting ring mechanism, and the spring pulling back the pin from within the arpeture assembly, both will no reset the arpeture lever on the mounting ring. (Sorry, I am no doubt using part descriptions, but I hope you get the general idea

The mount ring from what I understand, consists of two parts: The outer ring, that connects to the camera body, and an inner ring. By removing the shorter screws from the mounting ring, the two pieces will seperate. It is my understanding that there are ball bearing between the two pieces. I have not as of yet, seperated these two pieces. (A bit gun shy, you might say) . I am assuming at this point that the ball bearings are being pressed or compressed? I tried backing off all the screws and bringing them back down evenly and in rotation. I am able to get them all down, but not particularly tight. The mechanism will work, but getting them all down tight is proving to be an exercise in minute adjustments. Am I on the right track here, or is symptomatic of some other issue.
Is there some magic involved here, or is this lens indeed possessed?

MrFizzbin · Sep 2, 2012

Udate: All is well... opened up the mounting plate and one of the 4 bands that were sitting in a groove had fallen out of there. Put it back into the grove and the aperture preview lever moves freely now. But it makes me wonder: I was expecting 4 ball bearings. Might a previous repair job lost the ball bearings and the person substituted them with 4 bands? This is an earlier model from what I can see (the serial number starts with 200) maybe this was the mechanism back then?

Anyway..time to put this lens to work!

Minolta Rokkor MC PG f 1.2

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